feat: add Docker deployment configuration

Add backend and frontend Dockerfiles, docker-compose setup with nginx
reverse proxy, .dockerignore files and Makefile for dev/prod workflows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,14 @@
+.git
+.venv
+venv
+__pycache__
+*.pyc
+node_modules
+frontend/dist
+data
+*.egg-info
+.mypy_cache
+.ruff_cache
+.pytest_cache
+.vscode
+.idea